(Not Applicable)
(Not Applicable)
The present invention relates generally to hand-held vacuum pumps, and more particularly to a vacuum pump having a rod end of a pivot lever thereof for substantially axial movement of a piston rod.
Some examples of prior art hand-held vacuum pumps are disclosed in U.S. Pat. Nos. 4,954,054 and 4,775,302. Such hand-held vacuum pumps generally include a housing structure having a cylinder formed therein. A piston is movable in slidable engagement with the cylinder for forming a vacuum chamber within the housing structure. A port is provided to the vacuum chamber. The movement of the piston is actuated though the use of a piston rod which extends axially from the piston as well as the cylinder about the piston. Extending from the housing is typically a forward handle. The vacuum pump additionally includes a pivot lever. The pivot lever includes a rod end, an opposing handle end and a central attachment point. The rod end is rotatably connected to the piston rod and the cental attachment point is rotatably connected to the housing. In this regard, a linkage is formed such that clasped engagement of the forward handle and the handle end of the pivot lever causes a rotation or pivoting of the pivot lever about the central attachment point. This results in the piston end of the pivot lever moving in an arced path. While such an arced path includes a substantial axial component along the piston rod for drawing the piston rod and attached piston, there is an inherent transverse component which is undesirable.
It is contemplated that transverse or lateral movement of the piston rod results in misalignment of the piston within the cylinder. This can result in piston-to-cylinder seal problems thereby adversely affecting the efficient creation and/or maintenance of a vacuum within the cylinder. Accordingly, there is a need in the art for an improved vacuum pump in comparison to the prior art.
In accordance with an embodiment of the present invention, there is provided a hand-held vacuum pump. The vacuum pump is provided with a piston for drawing a vacuum. The vacuum pump is further provided with a piston rod having a piston end and a distal end. The piston end is attached to the piston. The vacuum pump is further provided with a pivot lever having a rod end, a handle end, and a pivot interface pivot interface disposed therebetween. The rod end is rotatably attached to the distal end of the piston rod. The vacuum pump is further provided with a pivot support having a support interface. The support interface and the pivot interface are cooperatively sized and configured to translate the rod end of the pivot lever for substantially axial movement of the piston rod upon rotation of the pivot lever about the support interface in response to actuation of the handle end of the pivot lever.
According to an aspect of the present invention, the pivot interface has at least two stepped pivot members. Further, the support interface has at least two stepped support members which are sized and configured to sequentially cradle respective ones of the at least two stepped pivot members for rotating the pivot lever about the support interface.
In an embodiment of the present invention, the support interface and the pivot interface are cooperatively sized and configured to translate the rod end of the pivot lever along sequential arced paths associated with respective cradling of the stepped pivot members with the stepped support members. It is contemplated that substantially axial movement of the piston rod results upon rotation of the pivot lever about the support interface in response to actuation of the handle end of the pivot lever. In this regard, such arced paths are contemplated to merge into each other resulting in a substantially linear path in comparison to prior art single pivot point lever movement along a single arced path. Preferably, the at least two stepped support members comprises three stepped support members, and the at least two stepped support members comprises three stepped support members. Further, the stepped pivot members may be convex V-shaped and the stepped support members may be concave V-shaped. In addition, the vacuum pump may include a forward handle disposed in fixed relation to the pivot support for actuating the piston upon clasped engagement of the forward handle and the handle end of the pivot lever towards each other. The pivot support may be integrated with the forward handle. Further, the pivot lever may include a rotational stop sized and configured to engage the pivot support for preventing rotation of the pivot lever.
As such, based on the foregoing, the present invention mitigates the inefficiencies and limitations associated with prior art vacuum pump designs. Advantageously, the support interface and the pivot interface are specifically sized and configured to translate the rod end of the pivot lever for substantially axial movement of the piston rod. This is because the location about which the pivot lever pivots or rotates is not fixed in relation to the pivot support, but rather multiple pivot locations may be realized. This in effect results in multiple arced paths or segments in which the piston end of the pivot lever travels. Such arced paths are contemplated to merge into each other. In comparison to prior art designs having a single point of rotation, the design of the present invention results in less transverse or lateral movement of the piston end of the pivot lever. This effectively breaks a single arced path into several shorter merging arced paths, which forms a substantially straight path by comparison.
Another advantage of the present invention is that the associated pivot lever may be reduced in sizing, thereby reducing the overall sizing the vacuum pump in general. This is because, the prior art single pivot point designs, the amount of transverse or lateral movement of the piston end of the pivot lever is a function of the distance from the pivot end to the pivot point. The shorter the distance (i.e., radius), the tighter the associated arc. As such, in order to achieve a certain maximum transverse movement specification, the pivot lever and associated single pivot point is required to be at least a certain size. The present invention has the effect of uncoupling the nature of any transverse motion away from the overall sizing of the pivot lever and towards the configuration of the pivot and support interfaces. This allows for comparative reduction in pivot lever sizing and therefore a reduction in the overall sizing of the vacuum pump itself.
In addition, the use of the pivot interface and the support interface results in the aforementioned advantages without the utilization of additional moving parts in comparison to prior art single rotation point vacuum pump designs. In this respect, it is contemplated that various linkage arrangements could be implemented which include additional moving parts between a traditional single rotation point pivot lever and a piston, so as to facilitate mitigation of lateral or transverse forces being applied to the piston rod and piston arrangement. This would include a rotational attachment of the piston rod to the piston. As such, undesirable costs are associated with such parts or connections, including assembly thereof. Moreover, additional linkage elements tend to introduce tolerance and/or precision errors into the system associated with the controlled actuation of the movement of the piston rod. As the present invention avoids such problems as no additional moving linkage parts are required.
Accordingly, the present invention represents a significant advance in the art.